On Sun, Feb 25, 2018 at 03:35:39PM +0100, Kevin Kofler wrote:
> Tomasz Kłoczko wrote:
> > BTW size. Did you try to compile systemd with optimisation for size (-Os)?
> > 
> > There are many Linux packages which should be optimised for size
> > because they provide binaries which are speed critical like boot
> > loaders and boot tools (grub, lilo, gubby) some diagnostics and system
> > tools (dmidecode, strace, parted, shadow-utils, util-linux, lvm, mdadm
> > ..)
> > In many cases optimisations for size provides faster code at it has
> > lower probability generate CPU cache misses.
> 
> If -Os code is actually faster than -O2, then we should change the 
> distrowide default.

Dunno. Speed is complicated, since even though it's fairly easy to do
some microbenchmarking using unittests, it's hard to measure something
representative.

But size is easy:
$ du -s /var/tmp/inst-O*
74428 /var/tmp/inst-O3
56136 /var/tmp/inst-O3-lto
61992 /var/tmp/inst-Os
43572 /var/tmp/inst-Os-lto

(Those are installation sizes from DESTDIR=/var/tmp/inst... ninja -C
build install, unstripped, in kB.)

Zbyszek
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